What is a Post-Incident Review (PIR)?
A post-incident review is a structured analysis conducted after a service disruption to understand what happened, why it happened, and what changes will prevent it from happening again. Also known as a postmortem, it is the primary mechanism by which engineering teams learn from failures.
Definition
A Post-Incident Review (PIR) is a blameless, structured meeting and document that examines a service incident from detection through resolution. Its purpose is to identify root causes, document the timeline, assess impact, and produce actionable follow-up items that reduce the likelihood or impact of similar incidents in the future.
The emphasis on "blameless" is critical: PIRs focus on systemic improvements (better monitoring, safer deployment processes, improved runbooks) rather than assigning fault to individuals.
Why Post-Incident Reviews Matter
Incidents are inevitable. What separates resilient organizations from fragile ones is whether they learn from each failure or repeat the same mistakes.
Prevent Repeat Incidents
Without a PIR, the conditions that caused the incident remain in place. The same failure mode will recur — often at a worse time. PIRs produce concrete action items (add a health check, improve the deployment rollback process, add monitoring for a previously unmonitored dependency) that directly address root causes.
Build Institutional Knowledge
PIR documents become a searchable knowledge base. When a similar symptom appears months later, engineers can reference past PIRs to accelerate diagnosis. This is especially valuable as team members rotate or new engineers join — the knowledge survives personnel changes.
Improve Incident Response Process
Each PIR is an opportunity to evaluate how well the team responded. Was the MTTA acceptable? Was the right person paged? Were the runbooks helpful? Over time, this continuous feedback loop sharpens the team's incident response capabilities and reduces MTTR.
Foster a Learning Culture
Blameless PIRs signal that your organization values learning over punishment. Engineers are more likely to report issues, take calculated risks, and surface problems early when they know that failures are treated as learning opportunities rather than career-ending events.
How to Conduct a Blameless Post-Incident Review
1Schedule Promptly
Hold the review within 24-72 hours of incident resolution. Memories fade quickly — details that seem obvious today will be forgotten in a week. Block 30-60 minutes and invite all incident responders. Assign a facilitator (ideally someone not directly involved) to keep discussion productive.
2Reconstruct the Timeline
Walk through the incident chronologically. Use timestamps from monitoring tools, chat logs, and alert history to build an accurate picture. Document every significant event: when the issue started, when it was detected, when alerts fired, who responded, what actions were taken, and when service was restored.
3Identify Root Cause(s)
Use the "5 Whys" technique: keep asking "why" until you reach the systemic root cause. Most incidents have multiple contributing factors. A deployment failure might have root causes in: no canary deployment process, missing integration tests, and insufficient monitoring of the affected endpoint. Document all contributing factors, not just the trigger.
4Define Action Items
For each root cause, create specific, measurable action items. Each action item must have an owner and a deadline. Prioritize actions that prevent the same category of incident, not just the exact same incident. "Add monitoring for /api/checkout endpoint" is good. "Be more careful with deployments" is not actionable.
5Document and Share
Write up the PIR document using a consistent template (see below). Share it with the broader engineering team. Store PIR documents in a searchable location so they can be referenced during future incidents.
Post-Incident Review Template
A good PIR template ensures consistency and completeness. Here are the essential sections:
Incident Summary
Date, duration, severity level, incident commander, and a 2-3 sentence summary of what happened and its impact.
Impact Assessment
Number of affected users, affected services/features, duration of impact, revenue impact (if applicable), and SLA impact.
Timeline
Chronological list of events with timestamps. Include: issue start time, detection time, alert time, acknowledgement time, key investigation steps, mitigation applied, and resolution confirmed.
Root Cause Analysis
What caused the incident? Include the trigger (immediate cause) and contributing factors (systemic issues). Use the "5 Whys" to go beyond surface-level explanations.
What Went Well
What worked during the response? Fast detection? Good communication? Effective runbook? Acknowledging successes reinforces good practices.
What Could Be Improved
Where did the response fall short? Slow detection? Missing runbook? Unclear escalation? Confusing alerts? This feeds directly into action items.
Action Items
Concrete follow-up tasks with owner, deadline, and priority. Example: "Add HTTP health check for /api/payments endpoint — Owner: @jane — Due: Feb 28 — Priority: High"
Common PIR Anti-Patterns to Avoid
These are the most common ways post-incident reviews go wrong:
Blame-Driven Reviews
Focusing on "who" instead of "why" shuts down honest discussion. If people fear punishment, they will hide information, and your PIR will miss the real root causes. Replace "John pushed a bad deploy" with "Our deployment pipeline lacked a canary step, allowing the change to reach all users simultaneously."
Skipping the PIR for "Small" Incidents
Small incidents often reveal the same systemic issues as large ones — they just got lucky with timing or scope. If a P2 incident was 5 minutes away from being a P1, it deserves a PIR. The cost of a 30-minute review is minimal compared to the cost of the P1 it might prevent.
Vague Action Items
"Improve monitoring" is not an action item. "Add TCP health check for the Redis cluster on port 6379 with 30-second intervals" is. Every action item needs a specific deliverable, an owner, and a deadline. Vague action items are never completed.
Never Following Up on Action Items
The PIR meeting is not the end — it is the beginning. If action items are created but never tracked or completed, the PIR was a waste of time. Review outstanding PIR action items weekly. If an action item has been open for more than 2 weeks without progress, it needs to be re-prioritized or re-assigned.
Waiting Too Long
A PIR conducted 2 weeks after an incident loses critical context. Engineers forget details, chat logs get buried, and the urgency fades. Schedule the review within 24-72 hours. It does not have to be perfect — a timely, good-enough review is far more valuable than a delayed, thorough one.
PIR Metrics and Follow-Up
Track these metrics to measure the effectiveness of your PIR process over time:
PIR Completion Rate
What percentage of P1/P2 incidents have a completed PIR? Target: 100% for P1, 80%+ for P2. If PIRs are being skipped, investigate whether the process is too burdensome or if there is a cultural issue.
Action Item Completion Rate
What percentage of PIR action items are completed within their deadline? This is the most important PIR metric. A high PIR completion rate with a low action item completion rate means you are documenting problems but not fixing them.
Repeat Incident Rate
How often do incidents recur with the same root cause? If the same category of failure keeps happening, your PIR action items are not addressing the systemic issue. This metric directly measures whether your PIR process is working.
Time to PIR
How many hours/days between incident resolution and the PIR meeting? Target: under 72 hours. Track this to ensure reviews happen while context is fresh. If your average time-to-PIR is increasing, it may indicate scheduling friction or deprioritization.
The Role of Monitoring in PIRs
Good monitoring data is the foundation of an effective PIR. Precise timestamps from your monitoring system allow you to reconstruct the timeline accurately. Multi-region monitoring helps determine whether an issue was localized or global. Historical uptime data provides context for impact assessment. Without monitoring data, PIRs rely on memory and guesswork.
Frequently Asked Questions
What is the difference between a post-incident review and a postmortem?▼
When should you conduct a post-incident review?▼
Who should participate in a post-incident review?▼
How long should a post-incident review take?▼
What makes a post-incident review 'blameless'?▼
How do you track action items from a PIR?▼
Should PIR documents be shared publicly?▼
Related Glossary Terms
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